1 Non-astigmatic corneas |
2 Regular astigmatism |
(a) oval |
(b) prolate symmetric bow tie (PSBT) |
(c) prolate asymmetric bow tie (PABT) |
(d) oblate symmetric bow tie (OSBT) |
(e) oblate asymmetric bow tie (OABT) |
3 Irregular astigmatism |
(a) mixed |
(b) prolate irregular (PI) |
(c) oblate irregular (OI) |
(d) “horseshoe” pattern |
(e) “triple” pattern |
(f) steep/flat (SF) |
(g) localised steep (LS) |
(h) unclassified |